With the rapid increase in areal density of disc drives and continuing emphasis on reducing size, there is a persistent need to provide ever smaller disc storage systems. For example, one commercially available disc storage system is one inch long and five millimeters thick. A five millimeter thickness is sometimes known in the art as card type II, while a card type I is 3.3 millimeters thick. To produce a disc storage system only one inch long with the type I thickness of 3.3 millimeters has been beyond the capability in the art, due to difficulties that arise with such compact dimensions.
For example, the gap between the disc and the base deck of a disc storage system may be only 0.4 or 0.3 millimeters. If a disc storage system having a disc-deck gap in this range is dropped only around five feet, the resulting shock would likely be more than enough to deflect the outer diameter of a disc enough to strike the base deck. This interferes with the proper operation of the disc storage system, and is known as a non-operating shock. The risk of non-operating shock poses a substantial limitation to further progress in miniaturization and reliability of disc storage systems.
The shrinking of the disc-deck gap also poses an obstacle to further progress in the assembly of disc storage systems. During assembly, the disc is deposited onto the motor base assembly at a fairly high speed relative to the base deck on which the motor base assembly is disposed. The disc is intended to come to a sudden stop at rest parallel with the base deck and separated therefrom by the disc-deck gap, of perhaps 0.3 or 0.4 millimeters. Since the disc typically does not remain perfectly parallel to the base deck throughout this installation process, some portion of the outer diameter of the disc may be likely to strike the base deck before the disc becomes properly positioned on the motor base assembly. Depending on the incoming speed of the disc relative to the base deck, this may damage the disc. Trying to prevent the disc from striking the base deck and becoming damaged during installation therefore requires either a slower incoming speed for the disc relative to the base deck, which would slow down the assembly process cycle time; or greater precision in orientation of the disc relative to the base deck during the installation process, prior to the disc achieving its proper position on the motor base assembly. Either of these requirements would impose additional cost on the installation process and therefore a higher price for the disc storage system.
Past attempts to solve challenges such as these have included adding separate snubbers to a disc storage system. Traditional solutions have included, for example, a shroud mounted disc snubber, a circumferentially extending disc snubber, a snubber having a pivoting body, or a disc guard mounted to a housing adjacent to a disc.
Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.